With their backs nearing the wall, Rangers coach Alain Vigneault turned to a rookie one day after his 22nd birthday.

Pavel Buchnevich came into the lineup and made his NHL postseason debut in the Blueshirts’ 2-1 win over the Canadiens in Game 4 of their first-round series on Tuesday night at the Garden, knotting the best-of-seven contest at two games apiece.

When Vigneault approached Buchnevich before the game to see how he was feeling, he got a good answer from the affable young Russian.

“I told him [this is] the first playoff game and he told me, ‘No, no,’ he had some in the KHL,” Vigneault said about the Russian league Buchnevich had played in before coming over for his first North American season this year. “So it put me at rest there. But he seemed real good before the game, he seemed to be in a good space. I thought he went out on the ice and played a good game. Made some good plays with the puck.”

Buchnevich had been scratched for the first three games of the playoffs, including when the team was offensively stifled in the 3-1 loss in Game 3 on Sunday night. But bringing in Buchnevich for the rugged Tanner Glass allowed Vigneault to reunite a line with Chris Kreider and Mika Zibanejad, nicknamed “KZB” during a nice run early in the season.

“That line had some good zone time,” Vigneault said, “and they used their speed and their skill.”

Defenseman Nick Holden came back into the lineup after being a scratch in Game 3. Holden replaced Kevin Klein and started the game on the right side, paired with Marc Staal.

After Buchnevich’s line, Vigneault juggled his combinations quite a bit. He started the game with Jimmy Vesey-Derek Stepan-Rick Nash, J.T. Miller-Kevin Hayes-Mats Zuccarello and Michael Grabner-Oscar Lindberg-Jesper Fast.

Vigneault had seemingly sent out fake forward lines in warm-ups before Game 3, but that bit turned out not to be the coach’s subterfuge, instead a joke played by the Rangers’ veteran players.

As Vigneault explained in French on Tuesday morning, the joke was to confuse Daniel Lacroix, who is now an assistant coach with the Canadiens after serving one year under Vigneault in 2013-14, when the Rangers made a run to the Stanley Cup final. Lacroix had to come out to write down the opposition’s lines and bring a report back to Montreal head coach Claude Julien. The Rangers who knew him decided to play a prank — and it confused a lot of people.

Part of the reason the Rangers thought their power play had been 0-for-10 in the first three games of the series was because the Canadiens watched a lot of tape on them and had their tendencies down. (The same could be said for how the Rangers held the Canadiens power play to 0-for-7 in the opening two games before they went 2-for-3 in Game 3.)

“There’s no doubt that all teams in the playoffs spend a lot of time, watch a lot of prior games about certain tendencies that the opponent can have,” Vigneault said. “That’s about preparation, and it probably does make it a little bit more challenging for players on the ice to execute.” , and probably execute quicker to make those plays. It’s about playoff hockey and the preparation that goes with it.”

The Rangers went 0-for-2, and the Canadiens were 0-for-3 on the power play on Wednesday night.